Active material based closure hinge and latch assembly

ABSTRACT

Disclosed herein are active material based closure hinge assemblies, latch assemblies, and alignment methods. In one embodiment, a closure assembly is disclosed. The assembly includes a first hinge portion having one end attached to a closure, a second hinge portion attached to the first hinge portion having one end attached to a vehicle body, and an active material configured to provide the first hinge portion with up to six degrees of freedom relative to second hinge portion upon receipt of an activation signal and less than or equal to two degrees of freedom in the absence of the activation signal.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application is a divisional of and claims priority to U.S.patent application Ser. No. 12/683,127, filed Jun. 6, 2010, now allowed,which claims priority to Ser. No. 11/678,085, filed Feb. 23, 2007, nowU.S. Pat. No. 7,677,639, all of which are incorporated herein byreference in their entirety.

BACKGROUND

The present disclosure generally relates to an active material basedclosure hinge, an active material based latch, and an active materialbased alignment process, and more particularly, to a process foraligning closures to a frame.

The alignment as well as the flush and gap appearance of a vehicle dooris typically based on the visual inspection and experience of anassembly line technician. In other instances, handheld fixtures arespecially designed to align the door relative to predeterminedspecifications. In both cases, the process for adjusting the flush andgap appearance and aligning the vehicle door is manual. Current practiceis to deform the door, body and hinge sheet metal manually, by bending,twisting and shoving the door until it is visually acceptable. Also, thelatch position is adjusted by striking it in order to move it. Thismetal deformation and latch movement is unmeasured. The adjustability isgenerally limited and irreversible. Because the alignment process ismanual and based on visual inspection, it is difficult to quantitativelymeasure the door adjustment process. Without quantitative measurements,developing statistical process control techniques is impractical. As aresult, gap and flushness quality tends to be inconsistent from vehicleto vehicle.

There are two issues in making a door fit an opening. The first is thatthe door must be in the proper location and orientation (pose) withinthe opening. The second is that the contours of the door must match thecontours of the opening. The invention disclosed herein addresses thefirst issue directly.

To those skilled in the art, it is known that six independent degrees offreedom (three translational and three rotational) are enough to adjusta rigid body to a desired pose. The more degrees of freedom internal tothe hinges and latches, the less deformation that is required to adjustthe pose of the door. Current hinge systems may have two degrees offreedom for adjustment considering the latch and hinge mechanisms. Thus,sheet metal deformation may be required to adjust the pose.

Accordingly, there is a need for an improved closure hinge, latch andalignment process. It would be particularly advantageous if thedeformation needed for closure adjustment were internal to the hinge andlatch mechanisms themselves and thereby avoided deforming the sheetmetal of the body, doors and hinges. This would allow the alignmentprocess to be done in a consistent, quantifiable, and reversible manner.

SUMMARY OF THE INVENTION

Disclosed herein are active material based closure hinge assemblies,latch assemblies, and alignment methods. In one embodiment, a closureassembly, includes a first hinge portion having one end attached to aclosure, a second hinge portion attached to the first hinge portionhaving one end attached to a vehicle body, and an active materialconfigured to provide the first hinge portion with up to six degrees offreedom relative to second hinge portion upon receipt of an activationsignal and less than or equal to two degrees of freedom in the absenceof the activation signal.

In another embodiment, an adjustable latch assembly is disclosed. Theassembly includes a bracket having walls defining first and secondapertures. The assembly also includes a latch pin disposed in the firstand second apertures. The assembly further includes a spacerintermediate walls defining the first and second apertures and the latchpin, the spacer comprising an active material. Still further, theassembly includes a latch configured to engage the latch pin. Yetfurther, the assembly includes an activation device in operativecommunication with the active material, wherein the activation device isoperable to selectively apply an activation signal to the activematerial and effect a reversible change in at least one property of theactive material, wherein the change in the at least one property iseffective to provide up to six degrees of freedom to the latch pin, andless than or equal to two degrees of freedom in the absence of theactivation signal.

The above features and advantages and other features and advantages ofthe invention are readily apparent from the following detaileddescription of the invention when taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details appear, by way of example only,in the following detailed description of embodiments, the detaileddescription referring to the drawings in which:

FIG. 1 is a schematic illustration of one embodiment of an activematerial based adjustable closure hinge assembly;

FIG. 2 is a schematic illustration of one embodiment of an activematerial based closure latch assembly;

FIG. 3 is a flowchart of an embodiment of an active material basedclosure assembly alignment method;

FIG. 4 is an illustration of aligning a door using an active materialbased closure assembly showing (a) a rotationally misaligned door panel,(b) a translationally misaligned door panel, and (c) a properly aligneddoor panel; and

FIG. 5 is a schematic view of one embodiment of an active material basedadjustable closure hinge assembly.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is notintended to limit the present disclosure, its application or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

Active material based closure assemblies and methods for adjustablealignment of the closure relative to a frame are disclosed herein. Incontrast to prior art closure assembly alignment processes, the closureassemblies (hinge and latch) and methods disclosed herein areadvantageously based on active materials. As used herein, the term“closure” is intended to include any panel hingeably attached to aframe. For example, the term “closure” is intended to generally includea vehicle passenger door 412, vehicle hood 420, vehicle trunk 422, glovebox panel 424, center console panel 426, lift gates 428, tail gates 429,cargo latches, and the like. Moreover, the term “closure” could includea refrigerator door, cabinet door, or the like. In a preferredembodiment, the closure is related to a panel used in the assembly of avehicle, such as a door.

The term “vehicle body” as used herein generally refers to parts of thevehicle onto which the closure may be hingeably attached, and includes,without limitation, body panels 430, chassis 432, frame 434 andsub-frame components, jams 436, pillars 438, and the like. The term“active material” as used herein generally refers to a material thatexhibits a change in a property such as dimension, shape, shear force,or flexural modulus upon application of an activation signal. Suitableactive materials include, without limitation, shape memory polymers(SMP), shape memory alloys (SMA), magnetic shape memory alloys (MSMA),magnetorheological elastomers (MR elastomers), electroactive polymers(EAP's), combinations thereof, and the like. Depending on the particularactive material, the activation signal can take the form of withoutlimitation, an electric current, a temperature change, a magnetic field,a mechanical loading or stressing, and the like.

Also, as used herein, the terms “first”, “second”, and the like do notdenote any order or importance, but rather are used to distinguish oneelement from another, and the terms “the”, “a”, and “an” do not denote alimitation of quantity, but rather denote the presence of at least oneof the referenced item. Furthermore, all ranges directed to the samequantity of a given component or measurement is inclusive of theendpoints and independently combinable.

Turning now to FIG. 1, an exemplary active material based adjustableclosure hinge assembly, generally designated by reference numeral 10, isillustrated. The adjustable closure hinge assembly is not intended to belimited to this particular embodiment nor is it intended to be limitedto any specific active material therein. The adjustable closure hingeassembly 10 has a first hinge portion 14 having one end fastened to aclosure 12 and a second hinge portion 18 fastened to a vehicle body 16for receiving the closure. The first and the second hinge portions 14,18 include first aperture 15 and second aperture 19, respectively,defined by walls 21 and 23, respectively, in which there is disposed ahinge member 20. The hinge member 20 pivotally engages the first andsecond portions 14, 18 to effect movement of the closure 12 relative tothe vehicle body 16. The hinge member 20 may be any object suitable forconnecting the first and second portions 14 and 18 and allowing rotationbetween them, such as, a pintle, bolt, hitch, pin, hook, and the like.Similarly, the first and second hinge portions 14, 18 may be any supportgenerally known in the art that is suitable for receiving the hingemember 20 in order to hingeably attach the closure 12 to the vehiclebody 16. A spacer 24, intermediate the walls 21 and 23 which define theapertures of first and second hinge portions 14, 18, is made of anactive material and is disposed in the apertures so as to separate hingemember 20 from direct contact with the second hinge portion 18.Optionally, a sleeve 22 and a bushing 26 may also be disposed in theapertures 15, 19 on either side of the spacer 24 so as to separate thespacer 24 from direct contact with the hinge member 20 or the secondhinge portion 18. The sleeve and/or bushing themselves may be composedof active materials as well. The spacer 24 is in operative communicationwith an activation device 28. As will be apparent to those skilled inthe art in view of this disclosure, the activation device 28 can be incontact with the active material portions defining the spacer, sleeveand bushing, e.g., via a resistive heating element, or may be externallydisposed, e.g., a heat gun.

The activation signal provided by the activation device may include aheat signal, a magnetic signal, an electrical signal, a pneumaticsignal, a mechanical signal, and the like, and combinations comprisingat least one of the foregoing signals, with the particular activationsignal dependent on the materials and/or configuration of the activematerial. A heat signal may be applied for changing the property of theactive material fabricated from shape memory alloys and/or shape memorypolymers. An electrical signal may be applied for changing the propertyof the active material fabricated from electroactive materials,electrostatics, and/or electronic EAP's. A magnetic field may be applied(removed, or changed) for changing the property of the active materialfabricated from magnetostrive materials such as MSMA and MR elastomers.

Desirably, the change in the property of the active material remains forthe duration of the applied activation signal. Also desirably, upondiscontinuation of the activation signal, the property revertssubstantially to its original form prior to the change if no force isbeing applied. Conversely, if a force and/or load is being applied atthe time of deactivation, the property will lock in the new desired formupon deactivation. In this manner, reversibility and multiple resets foralignment can advantageously occur.

Depending on the particular closure hinge assembly chosen, the activematerial may be deformed as the correct alignment of the closurerelative to the vehicle body is established. The closure is held inplace as the active material is deactivated thereby locking thedeformation of the active material into the spacer. Optionally, theclosure may include a plurality of closure hinge assemblies at variouspoints about its perimeter. Multiple closure hinge assemblies mayprovide increased security, increased torsional stiffness, increasedenergy absorption in an impact event, and the like.

Turning now to FIG. 2, an exemplary embodiment of an adjustable latchassembly 200, for use with the above-described hinge assembly, isillustrated. The adjustable latch assembly is not intended to be limitedto this particular embodiment nor is it intended to be limited to anyspecific active material therein. The latch assembly 200 has a bracket210 having one end fastened to a vehicle body 212. The bracket 210includes apertures defined by walls 214 in which there is disposed alatch pin 216. A spacer 218, intermediate the walls 214, is made of anactive material and is disposed in the apertures defined by the walls214 so as to separate latch pin 216 from direct contact with the bracket210. The spacer 218 is in operative communication with an activationdevice 220. As will be apparent to those skilled in the art in view ofthis disclosure, the activation device 220 can be in contact with theactive material portions defining the spacer 218, e.g., via a resistiveheating element, or may be externally disposed, e.g., a heat gun. Alatch 222 is configured to engage the latch pin 216, thereby holding aswing closure (not shown) in place. The latch assembly 200, incombination with the above-disclosed hinge 10, allows for adjustablealignment of a closure relative to a vehicle body upon activation of theactive materials. As such, the methods and embodiments described beloware intended to include both active material based closure hingeassemblies as well as active material based latch assemblies.

FIG. 3 is a flow chart exemplifying one embodiment of a method forclosure alignment using an active material based closure hinge and latchassembly such as is described above. The flow chart contains optionalprocess steps indicated by dashed boxes. The method generally compriseshingeably attaching a closure to a vehicle body, e.g., a closure frame.The method includes aligning apertures disposed in a first hinge portionthat is attached to the closure with apertures disposed in a secondhinge portion attached to the vehicle body. A spacer formed of an activematerial is inserted into the apertures of the first and second hingeportions after which a hinge member is then disposed in the apertures topivotally connect the closure to the vehicle body. An activation deviceis in operative communication with the active material. To effectalignment of the closure relative to the vehicle body, the activematerial of the spacer is activated to cause a change in a property ofthe active material. For example, if the spacer were formed of a SMP,heating the SMP above the transition temperature of the lowertemperature phase would dramatically lower its modulus so as to permitmovement of the closure about the pivot axis of the hinge member. Theuse of SMP to describe the flow chart is exemplary; other types ofactive materials and their properties are discussed in more detailbelow. When the desired alignment tolerances are achieved, the activematerial is deactivated. For example, cooling the SMP below thetransition temperature of the lower temperature phase increases itsmodulus, thereby locking the closure in a fixed position relative to thevehicle body. The process may be repeated any number of desired times toaffect the desired flush and gap appearance. Furthermore, the processmay be repeated not only during manufacturing of the vehicle, but at anytime during the vehicle's use life.

Advantageously, the active material based closure hinge and latchassemblies used in the disclosed alignment process may have multiplemotion adjustment directions (e.g., up to six degrees of freedom). Forexample, the disclosed closure hinge assembly as described in FIG. 1 aswell as the latch assembly described in FIG. 2, have at least fourdegrees of freedom. The closure hinge assembly as described below inFIG. 5, has at least five degrees of freedom. Upon deactivation, or inthe absence, of the activation signal, the closure hinge and latchassemblies have less than or equal to two degrees of freedom. As is wellrecognized by those in the art, the degrees of freedom may include, forexample, pitch adjustment, sway adjustment, yaw adjustment, rolladjustment, surge adjustment, up-down adjustment, and the like.

As designated by the dashed boxes of FIG. 3, the above-disclosed methodcan further include optional process steps for aligning a closure. Forexample, the flush and gap appearance of the closure relative to thevehicle body can be measured. This may be quantitatively measured usinga vision sensor, or the like. Moreover, the process may further includedetermining the optimum pose of the door panel relative to the vehiclebody. For example, rigid body kinematics may be used to determine theoptimum pose and calculate the necessary movements for proper alignment.Even further, a fixturing device may be applied to the door panel priorto activating the active material of the adjustable hinge. After theactive material based hinge is activated, the fixturing device may movethe door panel to the desired location based on the movements calculatedby the rigid body kinematics step. Finally, once the active materialbased hinge is deactivated, the process may optionally include storingthe movement data to create statistical process control techniques andimprove closure alignment consistency from vehicle to vehicle.

FIGS. 4A-4C depict a vehicle 400 having a vehicle body 410 and a doorpanel 412 that are aligned according to the method of FIG. 3. Aplurality of active material based closure hinge assemblies and/or latchassemblies 414 are disposed about the vehicle door panel 412. Thebold-outlined rectangles indicate the location of the active materialbased closure hinge and latch assemblies 414 in each figure. Prior tothe closure alignment process (FIG. 3), a door panel when manuallymounted to the door frame may be rotationally misaligned (FIG. 4( a)),translationally misaligned (FIG. 4(b)), any combination of translationaland rotational misalignment, and the like. By using an active materialin the adjustable closure hinge and latch assemblies such as describedabove, a fixturing device can be used to align the door based onprevious quantitative measurements or pre-determined flush and gapappearance specifications. In this case, the active material isactivated during fixturing. The active material may then be deactivatedto hold the door panel in proper alignment relative to the vehicle body,as shown in FIG. 4( c). As illustrated, the disclosed active materialbased method provides for alignment in multiple directions.

FIG. 5 is another exemplary active material based adjustable closurehinge assembly, generally designated 500. Adjustable closure hingeassembly 500 has a first hinge portion 510 and a second hinge portion512. The first hinge portion 510 may be connected to a closure, whilethe second hinge portion 512 may be connected to a vehicle body. In thisparticular embodiment, first hinge portion 510 may be composed of anactive material. The active material could be, for example, an SMAhaving a porous structure, such as, open cell, mesh, and the like. Inoperation, the SMA first hinge portion 510 could be compressed involume, pseudoplastically, while in the lower temperature, lower modulusMartensite state, leaving a gap between the first hinge portion 510 andthe second hinge portion 512. The gap would allow for position alignmentof the closure relative to the vehicle body. Once the desired alignmentof the adjustable hinge is established, the SMA first hinge portion 510could then be heated above its phase transformation temperature, thusactivating the shape memory property of the SMA causing the first hingeportion 510 to expand and fill the gap between the first hinge portion510 and the second hinge portion 512. When the gap is filled, the firsthinge portion 510 frictionally engages the second hinge portion 512. TheSMA can be subsequently cooled to set the new deformed first hingeportion 510 and fix the desired position of the closure. Again,advantageously, the disclosed closure hinge has up to six degrees offreedom, thereby permitting alignment in up to six directions. Note thatan equally valid variant, for which the above process holds, is one inwhich MSMA is substituted for SMA and the application of a magneticfield is substituted for thermal activation.

As previously described, suitable active materials for grommet, spacers,hinge portions, and the like, include, without limitation, shape memorypolymers (SMP), shape memory alloys (SMA), magnetic shape memory alloys(MSMA), MR elastomers, and EAP's.

“Shape memory polymer” generally refers to a polymeric material, whichexhibits a change in a property, such as an elastic modulus, a shape, adimension, a shape orientation, or a combination comprising at least oneof the foregoing properties upon application of an activation signal.Shape memory polymers may be thermoresponsive (i.e., the change in theproperty is caused by a thermal activation signal), photoresponsive(i.e., the change in the property is caused by a light-based activationsignal), moisture-responsive (i.e., the change in the property is causedby a liquid activation signal such as humidity, water vapor, or water),or a combination comprising at least one of the foregoing.

Generally, SMPs are phase segregated co-polymers comprising at least twodifferent units, which may be described as defining different segmentswithin the SMP, each segment contributing differently to the overallproperties of the SMP. As used herein, the term “segment” refers to ablock, graft, or sequence of the same or similar monomer or oligomerunits, which are copolymerized to form the SMP. Each segment may becrystalline or amorphous and will have a corresponding melting point orglass transition temperature (Tg), respectively. The term “thermaltransition temperature” is used herein for convenience to genericallyrefer to either a Tg or a melting point depending on whether the segmentis an amorphous segment or a crystalline segment. For SMPs comprising(n) segments, the SMP is said to have a hard segment and (n−1) softsegments, wherein the hard segment has a higher thermal transitiontemperature than any soft segment. Thus, the SMP has (n) thermaltransition temperatures. The thermal transition temperature of the hardsegment is termed the “last transition temperature”, and the lowestthermal transition temperature of the so-called “softest” segment istermed the “first transition temperature”. It is important to note thatif the SMP has multiple segments characterized by the same thermaltransition temperature, which is also the last transition temperature,then the SMP is said to have multiple hard segments.

When the SMP is heated above the last transition temperature, the SMPmaterial can be imparted a permanent shape. A permanent shape for theSMP can be set or memorized by subsequently cooling the SMP below thattemperature. As used herein, the terms “original shape”, “previouslydefined shape”, and “permanent shape” are synonymous and are intended tobe used interchangeably. A temporary shape can be set by heating thematerial to a temperature higher than a thermal transition temperatureof any soft segment yet below the last transition temperature, applyingan external stress or load to deform the SMP, and then cooling below theparticular thermal transition temperature of the soft segment whilemaintaining the deforming external stress or load.

The permanent shape can be recovered by heating the material, with thestress or load removed, above the particular thermal transitiontemperature of the soft segment yet below the last transitiontemperature. Thus, it should be clear that by combining multiple softsegments it is possible to demonstrate multiple temporary shapes andwith multiple hard segments it may be possible to demonstrate multiplepermanent shapes. Similarly using a layered or composite approach, acombination of multiple SMPs will demonstrate transitions betweenmultiple temporary and permanent shapes.

For SMPs with only two segments, the temporary shape of the shape memorypolymer is set at the first transition temperature, followed by coolingof the SMP, while under load, to lock in the temporary shape. Thetemporary shape is maintained as long as the SMP remains below the firsttransition temperature. The permanent shape is regained when the SMP isonce again brought above the first transition temperature with the loadremoved. Repeating the heating, shaping, and cooling steps canrepeatedly reset the temporary shape.

Most SMPs exhibit a “one-way” effect, wherein the SMP exhibits onepermanent shape. Upon heating the shape memory polymer above a softsegment thermal transition temperature without a stress or load, thepermanent shape is achieved and the shape will not revert back to thetemporary shape without the use of outside forces.

As an alternative, some shape memory polymer compositions can beprepared to exhibit a “two-way” effect, wherein the SMP exhibits twopermanent shapes. These systems include at least two polymer components.For example, one component could be a first cross-linked polymer whilethe other component is a different cross-linked polymer. The componentsare combined by layer techniques, or are interpenetrating networks,wherein the two polymer components are cross-linked but not to eachother. By changing the temperature, the shape memory polymer changes itsshape in the direction of a first permanent shape or a second permanentshape. Each of the permanent shapes belongs to one component of the SMP.The temperature dependence of the overall shape is caused by the factthat the mechanical properties of one component (“component A”) arealmost independent of the temperature in the temperature interval ofinterest. The mechanical properties of the other component (“componentB”) are temperature dependent in the temperature interval of interest.In one embodiment, component B becomes stronger at low temperaturescompared to component A, while component A is stronger at hightemperatures and determines the actual shape. A two-way memory devicecan be prepared by setting the permanent shape of component A (“firstpermanent shape”), deforming the device into the permanent shape ofcomponent B (“second permanent shape”), and fixing the permanent shapeof component B while applying a stress.

It should be recognized by one of ordinary skill in the art that it ispossible to configure SMPs in many different forms and shapes.Engineering the composition and structure of the polymer itself canallow for the choice of a particular temperature for a desiredapplication. For example, depending on the particular application, thelast transition temperature may be about 0° C. to about 300° C. orabove. A temperature for shape recovery (i.e., a soft segment thermaltransition temperature) may be greater than or equal to about −30° C.Another temperature for shape recovery may be greater than or equal toabout 40° C. Another temperature for shape recovery may be greater thanor equal to about 100° C. Another temperature for shape recovery may beless than or equal to about 250° C. Yet another temperature for shaperecovery may be less than or equal to about 200° C. Finally, anothertemperature for shape recovery may be less than or equal to about 150°C.

Optionally, the SMP can be selected to provide stress-induced yielding,which may be used directly (i.e. without heating the SMP above itsthermal transition temperature to ‘soften’ it) to make the pad conformto a given surface. The maximum strain that the SMP can withstand inthis case can, in some embodiments, be comparable to the case when theSMP is deformed above its thermal transition temperature.

Although reference has been, and will further be, made tothermoresponsive SMPs, those skilled in the art in view of thisdisclosure will recognize that photoresponsive, moisture-responsive SMPsand SMPs activated by other methods may readily be used in addition toor substituted in place of thermoresponsive SMPs. For example, insteadof using heat, a temporary shape may be set in a photoresponsive SMP byirradiating the photoresponsive SMP with light of a specific wavelength(while under load) effective to form specific crosslinks and thendiscontinuing the irradiation while still under load. To return to theoriginal shape, the photoresponsive SMP may be irradiated with light ofthe same or a different specific wavelength (with the load removed)effective to cleave the specific crosslinks. Similarly, a temporaryshape can be set in a moisture-responsive SMP by exposing specificfunctional groups or moieties to moisture (e.g., humidity, water, watervapor, or the like) effective to absorb a specific amount of moisture,applying a load or stress to the moisture-responsive SMP, and thenremoving the specific amount of moisture while still under load. Toreturn to the original shape, the moisture-responsive SMP may be exposedto moisture (with the load removed).

Suitable shape memory polymers, regardless of the particular type ofSMP, can be thermoplastics, thermosets-thermoplastic copolymers,interpenetrating networks, semi-interpenetrating networks, or mixednetworks. The SMP “units” or “segments” can be a single polymer or ablend of polymers. The polymers can be linear or branched elastomerswith side chains or dendritic structural elements. Suitable polymercomponents to form a shape memory polymer include, but are not limitedto, polyphosphazenes, poly(vinyl alcohols), polyamides, polyimides,polyester amides, poly(amino acid)s, polyanhydrides, polycarbonates,polyacrylates, polyalkylenes, polyacrylamides, polyalkylene glycols,polyalkylene oxides, polyalkylene terephthalates, polyortho esters,polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyesters,polylactides, polyglycolides, polysiloxanes, polyurethanes, polyethers,polyether amides, polyether esters, and copolymers thereof. Examples ofsuitable polyacrylates include poly(methyl methacrylate), poly(ethylmethacrylate), poly(butyl methacrylate), poly(isobutyl methacrylate),poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(laurylmethacrylate), poly(phenyl methacrylate), poly(methyl acrylate),poly(isopropyl acrylate), poly(isobutyl acrylate) andpoly(octadecylacrylate). Examples of other suitable polymers includepolystyrene, polypropylene, polyvinyl phenol, polyvinylpyrrolidone,chlorinated polybutylene, poly(octadecyl vinyl ether), poly (ethylenevinyl acetate), polyethylene, poly(ethylene oxide)-poly(ethyleneterephthalate), polyethylene/nylon (graft copolymer),polycaprolactones-polyamide (block copolymer), poly(caprolactone)diniethacrylate-n-butyl acrylate, poly(norbornyl-polyhedral oligomericsilsequioxane), polyvinylchloride, urethane/butadiene copolymers,polyurethane-containing block copolymers, styrene-butadiene blockcopolymers, and the like. The polymer(s) used to form the varioussegments in the SMPs described above are either commercially availableor can be synthesized using routine chemistry. Those of skill in the artcan readily prepare the polymers using known chemistry and processingtechniques without undue experimentation.

As will be appreciated by those skilled in the art, conductingpolymerization of different segments using a blowing agent can form ashape memory polymer foam, for example, as may be desired for someapplications. The blowing agent can be of the decomposition type(evolves a gas upon chemical decomposition) or an evaporation type(which vaporizes without chemical reaction). Exemplary blowing agents ofthe decomposition type include, but are not intended to be limited to,sodium bicarbonate, azide compounds, ammonium carbonate, ammoniumnitrite, light metals which evolve hydrogen upon reaction with water,azodicarbonamide, N,N′ dinitrosopentamethylenetetramine, and the like.Exemplary blowing agents of the evaporation type include, but are notintended to be limited to, trichloromonofluoromethane,trichlorotrifluoroethane, methylene chloride, compressed nitrogen, andthe like.

Similar to shape memory polymers, shape memory alloys exist in severaldifferent temperature-dependent phases. The most commonly utilized ofthese phases are the so-called martensite and austenite phases. In thefollowing discussion, the martensite phase generally refers to the moredeformable, lower temperature phase whereas the austenite phasegenerally refers to the more rigid, higher temperature phase. When theshape memory alloy is in the martensite phase and is heated, it beginsto change into the austenite phase. The temperature at which thisphenomenon starts is often referred to as austenite start temperature(As). The temperature at which this phenomenon is complete is called theaustenite finish temperature (Af). When the shape memory alloy is in theaustenite phase and is cooled, it begins to change into the martensitephase, and the temperature at which this phenomenon starts is referredto as the martensite start temperature (Ms). The temperature at whichaustenite finishes transforming to martensite is called the martensitefinish temperature (Mf). Generally, the shape memory alloys are softerand more easily deformable in their martensitic phase and are harder,stiffer, and/or more rigid in the austenitic phase. In view of theforegoing properties, expansion of the shape memory alloy is preferablyat or below the austenite transition temperature (at or below As).Subsequent heating above the austenite transition temperature causes theexpanded shape memory alloy to revert back to its permanent shape. Thus,a suitable activation signal for use with shape memory alloys is athermal activation signal having a magnitude to cause transformationsbetween the martensite and austenite phases.

The temperature at which the shape memory alloy remembers its hightemperature form when heated can be adjusted by slight changes in thecomposition of the alloy and through heat treatment. In nickel-titaniumshape memory alloys, for instance, it can be changed from above about100° C. to below about −100° C. The shape recovery process occurs over arange of just a few degrees and the start or finish of thetransformation can be controlled to within a degree or two depending onthe desired application and alloy composition. The mechanical propertiesof the shape memory alloy vary greatly over the temperature rangespanning their transformation, typically providing shape memory effects,superelastic effects, and high damping capacity.

Suitable shape memory alloy materials include, but are not intended tobe limited to, nickel-titanium based alloys, indium-titanium basedalloys, nickel-aluminum based alloys, nickel-gallium based alloys,copper based alloys (e.g., copper-zinc alloys, copper-aluminum alloys,copper-gold, and copper-tin alloys), gold-cadmium based alloys,silver-cadmium based alloys, indium-cadmium based alloys,manganese-copper based alloys, iron-platinum based alloys,iron-palladium based alloys, and the like. The alloys can be binary,ternary, or any higher order so long as the alloy composition exhibits ashape memory effect, e.g., change in shape orientation, changes in yieldstrength, and/or flexural modulus properties, damping capacity,superelasticity, and the like. Selection of a suitable shape memoryalloy composition depends on the temperature range where the componentwill operate.

Magnetic Shape Memory Alloys (MSMA) function in a manner similar to SMA,but operate under response to magnetic activation signals as opposed totemperature-based signals. MSMA are known to display excellent shapememory response speed. MSMA have a phase transition structure (a twincrystal structure). These twins have different magnetic andcrystallographic orientations. When a magnetic field is applied to theMSMA, the martensitic unit cells (magnetization vectors in the cells)are reoriented along a magnetic field to induce strain resulting in theshape change of the element. Typical MSMA materials include, but are notintended to be limited to, iron-based MSMA such Fe—Pd and Fe—Pt alloys,copper-based MSMA such as Cu—Al and Cu—Al—Mn alloys, and nickel-basedalloys, such as Ni—Mn—Ga and Ni—Co—Al alloys. Suitable magneticmaterials further include, but are not intended to be limited to, softor hard magnets; hematite; magnetite; magnetic material based on iron,nickel, and cobalt, alloys of the foregoing, or combinations comprisingat least one of the foregoing, and the like. Alloys of iron, nickeland/or cobalt, can comprise aluminum, silicon, cobalt, nickel, vanadium,molybdenum, chromium, tungsten, manganese and/or copper.

Magnetorheological (MR) elastomers are a group of smart materials whosemodulus can be controlled by the application of an external magneticfield. MR elastomer materials include, but are not intended to belimited to, an elastic polymer matrix comprising a suspension offerromagnetic or paramagnetic particles. Suitable particles includeiron; iron alloys, such as those including aluminum, silicon, cobalt,nickel, vanadium, molybdenum, chromium, tungsten, manganese and/orcopper; iron oxides, including Fe₂O₃ and Fe₃O₄; iron nitride; ironcarbide; carbonyl iron; nickel and alloys of nickel; cobalt and alloysof cobalt; chromium dioxide; stainless steel; silicon steel; and thelike.

The particle size should be selected so that the particles exhibitmultiple magnetic domain characteristics when subjected to a magneticfield. Diameter sizes for the particles can be less than or equal toabout 1,000 micrometers, with less than or equal to about 500micrometers preferred, and less than or equal to about 100 micrometersmore preferred. Also preferred is a particle diameter of greater than orequal to about 0.1 micrometer, with greater than or equal to about 0.5more preferred, and greater than or equal to about 10 micrometersespecially preferred. The particles are preferably present in an amountbetween about 5.0 to about 50 percent by volume of the total MRelastomer composition.

Suitable polymer matrices include, but are not limited to,poly-alpha-olefins, natural rubber, silicone, polybutadiene,polyethylene, polyisoprene, and the like.

Electroactive polymers include those polymeric materials that exhibitpyroelectric, or electrostrictive properties in response to electricalor mechanical fields. An example of an electrostrictive-graftedelastomer with a piezoelectric poly(vinylidenefluoride-trifluoro-ethylene) copolymer. This combination has the abilityto produce a varied amount of ferroelectric-electrostrictive molecularcomposite systems. These may be operated as a piezoelectric sensor oreven an electrostrictive actuator.

Materials suitable for use as an electroactive polymer may include anysubstantially insulating polymer or rubber (or combination thereof) thatdeforms in response to an electrostatic force or whose deformationresults in a change in electric field. Exemplary materials suitable foruse as a pre-strained polymer include silicone elastomers, acrylicelastomers, polyurethanes, thermoplastic elastomers, copolymerscomprising PVDF, pressure-sensitive adhesives, fluoroelastomers,polymers comprising silicone and acrylic moieties, and the like.Polymers comprising silicone and acrylic moieties may include copolymerscomprising silicone and acrylic moieties, polymer blends comprising asilicone elastomer and an acrylic elastomer, for example.

Materials used as an electroactive polymer may be selected based on oneor more material properties such as high electrical breakdown strength,a low modulus of elasticity—(for large or small deformations), a highdielectric constant, and the like. In one embodiment, the polymer isselected such that is has an elastic modulus at most about 100 MPa. Inanother embodiment, the polymer is selected such that is has a maximumactuation pressure between about 0.05 MPa and about 10 MPa, andpreferably between about 0.3 MPa and about 3 MPa. In another embodiment,the polymer is selected such that is has a dielectric constant betweenabout 2 and about 20, and preferably between about 2.5 and about 12. Thepresent disclosure is not intended to be limited to these ranges.Ideally, materials with a higher dielectric constant than the rangesgiven above would be desirable if the materials had both a highdielectric constant and a high dielectric strength. In many cases,electroactive polymers may be fabricated and implemented as thin filmsThicknesses suitable for these thin films may be below 50 micrometers.

As electroactive polymers may deflect at high strains, electrodesattached to the polymers should also deflect without compromisingmechanical or electrical performance. Generally, electrodes suitable foruse may be of any shape and material provided that they are able tosupply a suitable voltage to, or receive a suitable voltage from, anelectroactive polymer. The voltage may be either constant or varyingover time. In one embodiment, the electrodes adhere to a surface of thepolymer. Electrodes adhering to the polymer are preferably compliant andconform to the changing shape of the polymer. Correspondingly, thepresent disclosure may include compliant electrodes that conform to theshape of an electroactive polymer to which they are attached. Theelectrodes may be only applied to a portion of an electroactive polymerand define an active area according to their geometry. Various types ofelectrodes suitable for use with the present disclosure includestructured electrodes comprising metal traces and charge distributionlayers, textured electrodes comprising varying out of plane dimensions,conductive greases such as carbon greases or silver greases, colloidalsuspensions, high aspect ratio conductive materials such as carbonfibrils and carbon nanotubes.

Materials used for electrodes of the present disclosure may vary.Suitable materials used in an electrode may include graphite, carbonblack, colloidal suspensions, thin metals including silver and gold,silver filled and carbon filled gels and polymers, and ionically orelectronically conductive polymers. It is understood that certainelectrode materials may work well with particular polymers and may notwork as well for others. By way of example, carbon fibrils work wellwith acrylic elastomer polymers while not as well with siliconepolymers.

Advantageously, the above noted active material based closure hinge,latch assemblies, and closure alignment process provide a moreconsistent and quantifiable method compared to current closure alignmentprocesses. In addition to providing reversibility, the processes offeropportunities for the development of statistical process controltechniques for the closure alignment process. The statistical controldata can improve process efficiency as well as consistency from vehicleto vehicle. Furthermore, it should be recognized by those skilled in theart that the active material based closure hinge assembly may beconfigured for attachment of any hinged panel to the vehicle body.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments disclosed, but that theinvention will include all embodiments falling within the scope of theapplication.

1. A closure assembly, comprising: a first hinge portion having one endattached to a closure; a second hinge portion hingeably attached to thefirst hinge portion and having one end attached to a vehicle body; andan active material that provides the first hinge portion with up to sixdegrees of freedom relative to the second hinge portion upon receipt ofan activation signal, and less than or equal to two degrees of freedomin the absence of the activation signal.
 2. The closure assembly ofclaim 1, wherein the first hinge portion has a first aperture, thesecond hinge portion has a second aperture coaxially aligned with thefirst aperture, and further comprising a hinge member disposed in thefirst and second apertures for attaching the first and second hingeportions, and a spacer intermediate walls defining the first and secondapertures and the hinge member, wherein the spacer comprises the activematerial.
 3. The closure assembly of claim 1, wherein the first hingeportion is formed of the active material and the second hinge portion isdisposed inside the first hinge portion such that when the activematerial of the first hinge portion is activated, the second hingeportion is in frictional communication with the first hinge portion. 4.The closure assembly of claim 1, wherein the active material comprises ashape memory alloy, a ferromagnetic shape memory alloy, a shape memorypolymer, a magnetorheological elastomer, an electroactive polymer, orcombinations comprising at least one of the foregoing active materials.5. The closure assembly of claim 1, wherein the activation signalcomprises a thermal activation signal, an electric activation signal, achemical activation signal, a magnetic activation signal, a mechanicalload, or a combination comprising at least one of the foregoingactivation signals.
 6. The closure assembly of claim 1, wherein theactive material is configured to undergo a reversible change in at leastone property, wherein the reversible change in the at least one propertycomprises a change in a shape, a shear force, a shape orientation, aflexural modulus, or combinations comprising at least one of theforegoing properties.
 7. An adjustable latch assembly, comprising: abracket having walls defining first and second apertures; a latch pindisposed in the first and second apertures; a spacer intermediate wallsdefining the first and second apertures and the latch pin, the spacercomprising an active material; a latch configured to engage the latchpin; and an activation device in operative communication with the activematerial, wherein the activation device is operable to selectively applyan activation signal to the active material and effect a reversiblechange in at least one property of the active material, wherein thechange in the at least one property is effective to provide up to sixdegrees of freedom to the latch pin, and less than or equal to twodegrees of freedom in the absence of the activation signal.
 8. Theclosure assembly of claim 2, wherein the spacer is disposed intermediatea sleeve and a bushing, the sleeve is disposed between the spacer andthe hinge member, and the bushing is disposed between the spacer and thewalls defining the first and second apertures.
 9. The closure assemblyof claim 8, wherein the bushing or sleeve, or both of them, comprise anactive material.
 10. The adjustable latch assembly of claim 7, whereinthe spacer is disposed intermediate a sleeve and a bushing, the sleeveis disposed between the spacer and the latch pin, and the bushing isdisposed between the spacer and the walls defining the first and secondapertures.
 11. The adjustable latch assembly of claim 10, wherein thebushing or sleeve, or both of them, comprise an active material.